Fossil Friday!

This week we have a very special fossil courtesy of Fossil Friday fan Dan Phelps—who also happens to be the president of the Kentucky Paleontological Society. What could it be? Looks like some sort of plant pod to me, or an ancient sloth zipper?

No, this is an invertebrate found in what is now Indiana. The first person to identify it wins bragging rights for the week. Sorry, Dan, you don't get to guess this week, though you are welcome to taunt the commenters!